FDNY WRITTEN EXAM QUESTIONS & ANSWERS
A more efficient centrifugal compressor operation results from - Answer -Lowering the
condensing pressure
The heat removed from the refrigerant in a condenser is - Answer -Sensible and latent
heat
According to the New York City fire code, refrigerant containers must - Answer -Be
approved by the US Department of Transportation
The cylinder unloader works by - Answer -Keeping the suction valve opened while the
compressor is in the return stroke
In most semi-hermetic compressors, the suction vapor is used to - Answer -Cool the
motor
The amount of refrigerant that flows through the orifices of an economizer is determined
by the - Answer -Difference between the high side and low side pressure
The installation of an inline refrigerant cleaning system is advisable to - Answer -
Remove impurities from the system
The type of refrigerant system least likely to leak refrigerant into the building space is -
Answer -The indirect system
The compression ratio for a reciprocating compressor with a suction pressure of 65
PSIG and a discharge pressure of 120 PSIG is closest to - Answer -1.69
A superheated vapor is - Answer -Dry vapor above the saturation temperature
A condenser water pump cavitating is most likely caused by - Answer -A faulty cooling
tower water level controller
A centrifugal water pump is known as a lift pump when - Answer -The water supply to
the pump suction inlet is below the pump level
A TXV is used to maintain constant - Answer -Evaporator superheat
A chilled water supply of 55°F for human comfort is - Answer -Too high for human
comfort purpose
The packing gland of a centrifugal pump serves to - Answer -Keep air out of the pumps
when the impeller housing is under negative pressure
,Capacity control of a reciprocating hermetic compressor is typically achieved through -
Answer -Operation of the hot gas bypass valve
The most important reason to sub-cool the refrigerant in the condenser is to ensure that
- Answer -A pure liquid refrigerant will enter the metering device
If a compressor discharge temperature has dropped significantly and the suction line
pressure is high, this may be caused by - Answer -An expansion valve that is open too
wide
A low side float valve is used to maintain - Answer -The level of the refrigerant in the
evaporator
The ASHRAE refrigerant safety classification indicating no flammability and lower
toxicity is - Answer -A1
When an expansion valve is operating properly, the end of the evaporator will contain -
Answer -Only superheated vapor
Information not contained in a Material Safety Data Sheet (MSDS) includes - Answer -
Cost of the material
In a steam turbine, the Kingsbury thrust bearing functions to - Answer -Maintain axial
positioning of the rotor shaft
A centrifugal water pump is considered fully primed when - Answer -The pump is full of
liquid
To avoid collapsing tubing when making bends, a refrigerant engineer should use -
Answer -Lever type tubing bender
A reciprocating compressor making a clicking sound during operation, if not caused by
worn parts, is probably due to - Answer -Slugging of the liquid refrigerant
For a refrigerant to become superheated, it must be heated in a section of the low side
refrigerant line - Answer -Where no liquid refrigerant is present
After all liquid refrigerant has been recovered, the system - Answer -Should not be
opened until all vapor has been recovered
The removal rate of refrigerant using a portable compressor recovery unit gradually
slows down because - Answer -The vapor density is decreasing
If the water level in all cooling tower cells is very low, the immediate action should be to
- Answer -Add additional makeup water to the cooling tower
, The height of the water column, in feet, with a pressure gauge reading 140 PSIG is
closest to - Answer -323 feet
The device that protects a steam turbine from excessive speed is the - Answer -
Governor assembly
If a refrigeration compressor fails to turn on, after verifying the electrical circuit, the next
item to check would be the - Answer -Temperature and pressure controls
Of the refrigerants in commercial and industrial use, the one with the highest latent heat
and refrigerant effect is - Answer -Ammonia
The ASHRAE refrigerant safety group classification system is based on - Answer -
Flammability and toxicity
An example of an in-line refrigerant cleaning system for a centrifugal compressor
containing R123 refrigerant is - Answer -Refrigerant recycling
Information about the physical and chemical properties of a hazardous material can be
found in the - Answer -Material Safety Data Sheet (MSDS)
The function of the turbine auxiliary oil pump is to - Answer -Establish oil pressure
during turbine start-up
The rupture disc for a low-pressure centrifugal refrigeration machine is normally located
on the - Answer -Compressor suction
Ribbed metal piping is used for electrical wires connected to the refrigeration system
primarily because - Answer -It allows for flexibility and accounts for vibrations
If some of the cylinder unloaders on a multi-cylinder reciprocating compressor fail to
operate, one likely outcome is that - Answer -The chilled water temperature will
increase
If the suction gauge of a condenser water pump reads 55 PSI, draining the 75 feet long,
12-inch diameter pipe would yield approximately - Answer -440 gallons of water
A leak in the evaporator shell of a system using R123 refrigerant might result in -
Answer -A higher than normal high side pressure
The function of capacitors used on refrigeration motors is to - Answer -Store electrical
charges during starting and running the motor
A centrifugal refrigerant machine is best characterized as a - Answer -High volume, low
pressure machine
A more efficient centrifugal compressor operation results from - Answer -Lowering the
condensing pressure
The heat removed from the refrigerant in a condenser is - Answer -Sensible and latent
heat
According to the New York City fire code, refrigerant containers must - Answer -Be
approved by the US Department of Transportation
The cylinder unloader works by - Answer -Keeping the suction valve opened while the
compressor is in the return stroke
In most semi-hermetic compressors, the suction vapor is used to - Answer -Cool the
motor
The amount of refrigerant that flows through the orifices of an economizer is determined
by the - Answer -Difference between the high side and low side pressure
The installation of an inline refrigerant cleaning system is advisable to - Answer -
Remove impurities from the system
The type of refrigerant system least likely to leak refrigerant into the building space is -
Answer -The indirect system
The compression ratio for a reciprocating compressor with a suction pressure of 65
PSIG and a discharge pressure of 120 PSIG is closest to - Answer -1.69
A superheated vapor is - Answer -Dry vapor above the saturation temperature
A condenser water pump cavitating is most likely caused by - Answer -A faulty cooling
tower water level controller
A centrifugal water pump is known as a lift pump when - Answer -The water supply to
the pump suction inlet is below the pump level
A TXV is used to maintain constant - Answer -Evaporator superheat
A chilled water supply of 55°F for human comfort is - Answer -Too high for human
comfort purpose
The packing gland of a centrifugal pump serves to - Answer -Keep air out of the pumps
when the impeller housing is under negative pressure
,Capacity control of a reciprocating hermetic compressor is typically achieved through -
Answer -Operation of the hot gas bypass valve
The most important reason to sub-cool the refrigerant in the condenser is to ensure that
- Answer -A pure liquid refrigerant will enter the metering device
If a compressor discharge temperature has dropped significantly and the suction line
pressure is high, this may be caused by - Answer -An expansion valve that is open too
wide
A low side float valve is used to maintain - Answer -The level of the refrigerant in the
evaporator
The ASHRAE refrigerant safety classification indicating no flammability and lower
toxicity is - Answer -A1
When an expansion valve is operating properly, the end of the evaporator will contain -
Answer -Only superheated vapor
Information not contained in a Material Safety Data Sheet (MSDS) includes - Answer -
Cost of the material
In a steam turbine, the Kingsbury thrust bearing functions to - Answer -Maintain axial
positioning of the rotor shaft
A centrifugal water pump is considered fully primed when - Answer -The pump is full of
liquid
To avoid collapsing tubing when making bends, a refrigerant engineer should use -
Answer -Lever type tubing bender
A reciprocating compressor making a clicking sound during operation, if not caused by
worn parts, is probably due to - Answer -Slugging of the liquid refrigerant
For a refrigerant to become superheated, it must be heated in a section of the low side
refrigerant line - Answer -Where no liquid refrigerant is present
After all liquid refrigerant has been recovered, the system - Answer -Should not be
opened until all vapor has been recovered
The removal rate of refrigerant using a portable compressor recovery unit gradually
slows down because - Answer -The vapor density is decreasing
If the water level in all cooling tower cells is very low, the immediate action should be to
- Answer -Add additional makeup water to the cooling tower
, The height of the water column, in feet, with a pressure gauge reading 140 PSIG is
closest to - Answer -323 feet
The device that protects a steam turbine from excessive speed is the - Answer -
Governor assembly
If a refrigeration compressor fails to turn on, after verifying the electrical circuit, the next
item to check would be the - Answer -Temperature and pressure controls
Of the refrigerants in commercial and industrial use, the one with the highest latent heat
and refrigerant effect is - Answer -Ammonia
The ASHRAE refrigerant safety group classification system is based on - Answer -
Flammability and toxicity
An example of an in-line refrigerant cleaning system for a centrifugal compressor
containing R123 refrigerant is - Answer -Refrigerant recycling
Information about the physical and chemical properties of a hazardous material can be
found in the - Answer -Material Safety Data Sheet (MSDS)
The function of the turbine auxiliary oil pump is to - Answer -Establish oil pressure
during turbine start-up
The rupture disc for a low-pressure centrifugal refrigeration machine is normally located
on the - Answer -Compressor suction
Ribbed metal piping is used for electrical wires connected to the refrigeration system
primarily because - Answer -It allows for flexibility and accounts for vibrations
If some of the cylinder unloaders on a multi-cylinder reciprocating compressor fail to
operate, one likely outcome is that - Answer -The chilled water temperature will
increase
If the suction gauge of a condenser water pump reads 55 PSI, draining the 75 feet long,
12-inch diameter pipe would yield approximately - Answer -440 gallons of water
A leak in the evaporator shell of a system using R123 refrigerant might result in -
Answer -A higher than normal high side pressure
The function of capacitors used on refrigeration motors is to - Answer -Store electrical
charges during starting and running the motor
A centrifugal refrigerant machine is best characterized as a - Answer -High volume, low
pressure machine
